Frequency measurement is necessary for efficient AC power systems. There are two main types of frequency meters: electrical resonance circuits and ratiometers. Ferrodynamic and electromechanical meters are common frequency meter designs. A ferrodynamic meter uses a magnetizing coil and movable coil attached to a core to induce a current whose phase depends on inductance and capacitance. An electromechanical meter generates opposing torques from inductive and capacitive currents in fixed and moving coils to indicate frequency.

1. Submitted by:
Nalin Dubey
B.Tech (ECE)
130020204016
GD Goenka University
Measurement of frequency

2. What is frequency measurement
?
 It is the most necessary need for the
measurement in the AC power systems designed
to run efficiently.
 Frequency measurement can be done using
frequency meter.
 It is done for periodic electrical signals.
 There are two types of deflection meters:
1. Electrical Resonance Circuit
2. Ratiometer

3. Types of Frequency meter
Frequency
meter
Electrical
resonance
frequency
meter
Ferrodynamic type
frequency meter
Electrodynamomet
er type frequency
meter
Weston
frequency
meter
Ratiometer
type
frequency
meter

4. What is an Electrical Resonance
Frequency Meter ?

5. Ferrodynamic Type Frequency Meter

6. Ferrodynamic Type Frequency Meter
Construction:
 It has laminated core on which the magnetizing coil
is fixed.
 It also has a moving coil attached to the laminated
core which is movable.
 There is another terminal of the moving coil are
connected to the capacitor of suitable value.
 At the top of the moving coil there is a pivoting done
to attach the pointer to the moving coil.
 Then, further the pointer is attached to the
measuring scale

7. Ferrodynamic Type Frequency Meter
 Operation:
 The magnetizing coil carries a current I and this
current produces a flux ø.
 Flux ø being alternate in nature induces an E.M.F
“E” in the moving coil.
 The e.m.f induced causes a current in the moving
coil. The phase of this current depends upon
inductance “L” of the moving coil & capacitance “C”.

8. Electrodynamometer Type
Frequency Meter

9. Electrodynamometer Type
Frequency Meter
 Construction & Operation:
 There are two fixed coils in this circuit i.e.; Part1 & Part2.
 The part1 is connected in series with the L1 and C1 and
likewise on the part2 side.
 The current is passed within the arms of the two sides
and generate current I1 & I2 which then combines in the
moving coil and helps the needle to deflect on either
side.
 Torque on the movable element is directly proportional to
the current in the moving coil & this current is the sum of
current in 2 parts of fixed coil.
 One current coil is inductive while the other coil is
capacitive in nature. Torque produced by 2 currents I1 &
I2 will be in opposition on moving coil.

10. Weston Frequency Meter

11. Weston Frequency Meter
 Construction & Operation: